1. Field of the Invention
The present invention relates to a method of manufacturing a carbon electrode and a method of manufacturing a fused silica crucible, and more particularly, to a technique able to be applied to heating and melting vitreous silica powder by arc discharge for vitrification.
Priority is claimed on Japanese Patent Application No. 2008-248087, filed on Sep. 26, 2008, the content of which is incorporated herein by reference.
2. Description of the Related Art
A fused silica crucible used for pulling single-crystal silicon is manufactured mainly by arc melting. Briefly, this method is a method of manufacturing a fused silica crucible by accumulating a predetermined thickness of vitreous silica powder on an inner surface of a mold made of carbon so as to form a vitreous silica powder compact that is a vitreous silica-deposited layer, providing carbon electrodes above the vitreous silica powder compact, and heating the vitreous silica-deposited layer by the arc discharge for vitrification.
Japanese Patent No. 03647688 discloses a technique related to arc melting in a fused silica crucible manufacturing process by using arc melting, and JP-A-2002-68841 and JP-A-2001-097775 disclose techniques related to electrodes used for arc discharge. In addition, JP-A-2003-335532 discloses a description related to an inter-electrode distance for arc discharge.
In addition, due to resent demand for higher efficiency of a device operation, the diameter of a manufactured wafer has increased to over 300 mm, and for this, there is a requirement for a fused silica crucible used for pulling single crystals with a large diameter. In addition, due to demand for a reduction in size of a device or the like, there is a strong demand for improvements in crucible properties such as an internal state of a fused silica crucible, which may directly affect the properties of single crystals under pulling.